Vehicle sight windows and other surfaces often become dirty and in cold conditions also become coated with ice and/or snow. Vehicles having windshields and other sight windows (referred to as viewing surfaces) typically employ oscillating elastomeric blade windshield wipers to remove rain and snow from the exterior viewing surfaces of the vehicle. Such blades can be annoying as they move back and forth across the viewing surface, and often the motion is not rapid enough to satisfactorily remove rain and snow. Snow and ice can accumulate on the blades, requiring the driver of a vehicle to periodically manually clean the blades, which can create a safety hazard. The ice may also freeze the blades to the viewing surface when the vehicle is parked. Such blades also tend to smear the windshield, or other viewing surfaces, welding road tars and smudges against the viewing surface. Additionally, they can cause immediate damage to an optical surface if there are any hard particles (e.g. sand) on the viewing surface to be dragged across the surface by the wiper. Wipers also slowly degrade the viewing surface over time through surface erosion due to repeated sliding contact between the wiper blade squeegee and the viewing surface.
Because blade squeegees are made from relatively soft materials (typically rubber or synthetic rubber) they are subject to wear, and become hard, dry and brittle due to aging, therefore requiring routine replacement. Additionally, vision through the viewing surface is degraded during the washing cycle for a relatively long time and wiper reliability is dependant upon motors (usually electric), linkages, and bushings/bearings. Very perceptible and annoying sounds may also emerge from the actuating mechanism as it reverses at the end of each stroke, creating squeaks as the blades cub against the glass.
A number of attempts have been made to avoid the use of such conventional elastomeric blades. U.S. Pat. No. 1,854,758, issued Apr. 19, 1932, to Noble, describes a windshield cleaner which directs hot air from the engine compartment against the exterior surface of a windshield. The hot air is gathered against a collecting deflector in the engine compartment that receives rearwardly flowing air as a result of the vehicle's forward motion. The air escapes through openings formed at the rear edges of the hood wings by the mounting of the device therein and external baffles direct the air against the windshield.
U.S. Pat. No. 1,932,798, issued Oct. 31, 1933, to Millard, describes various embodiments of arrangements for directing hot air at the exterior surface of a windshield, including the use of a blower and the injection of glycerin into the air stream.
U.S. Pat. No. 2,032,998, issued Mar. 3, 1936, to Mickadeit, describes an air-heated windshield in which air flows by convection into a coil wrapped around the exhaust manifold of a vehicle, then flows through control devices, and finally flows through perforated manifolds surrounding the windshield and across the windshield.
U.S. Pat. No. 2,926,396, issued Mar. 1, 1960, to Hess, describes a system for blowing heated air against a windshield in which heated air from a blower in the engine compartment is mixed with an air stream created by the forward motion of the vehicle.
U.S. Pat. No. 3,769,898, issued Nov. 6, 1973, to Ide, describes a system for blowing hot air across a windshield which includes blowers disposed in ducts behind the vehicle's radiator. The air is ducted to the lower edge of the windshield where it discharges against the windshield through slits.
These attempts to eliminate the need for wipers using high velocity airflow over a windshield have many drawbacks. Various disadvantages of the above devices are poor air flow, poor air distribution, and complexity. Additionally, all of these devices have upwardly open air outlets which gather fallen dirt, leaves and other debris.
These devices and methods are more effective for continuous rain removal rather than cleaning. However, if a fluid spray were added to adapt this method for cleaning, the system would have many disadvantages. First, the system would need continuous, high capacity air supply. Second, the system would need a separate control system for the fluid supply. Lastly, the effectiveness of the system would be limited because a continuous airflow is not very effective at dislodging dirt.
Therefore, there is a need for a surface washing system that does not include the use of wiper blades that does not require continuous, high capacity air supply washing, that does not need a separate control system for the fluid supply, and that is very effective at dislodging dirt from the surface.